Pressure operated mechanism



ec 4 l95l s. HACKNEY PRESSURE OPERATED MECHANISM 5 Sheets-Sheet l FiledDec. 21, 1948 QN x mwN Nw. ws xm.

Dec. 4, 1951 s. HACKNEY PRESSURE @PER/TED MECHANISM 5 Sheets-Sheet 3Filed Dec. 21, 1948 Dec. 4, 1951 s. HACKNEY 2,577,462

PRESSURE OPERATED MECHANISM Filed Dec. 21, 1948 5 Sheets-Sheet 4 Dec. 4,1951 s.- HACKNEY 2,577,462

PRESSURE OPERATED MECHANISM Filed Dec. 21, 1948 5 Sheets-Sheet 5 M-mm@ya i Patented ec. 4, i951 UNITED STATES PATENT QFFICEElectro-Hydraulics Limited, Warrington,

England, a company of Great Britain Application December 21, 1948,Serial No. 66,484 In Great Britain December 22, 1947 gency, that is tosay, cases in which the normalV supply of pressure fails.

as aircraft become larger and heavier, a state of aiairs is approachedwhere the'force required to operate the i'lying controls is so greatthat in some cases the pilot may not have sufcient physical strength tomove the flying control lever. For this and other reasons it becomesnecessary in power assisted ilying controls, that is flying controlsoperated by means of jacks or other motors, to incorporate a completeemergency system, and, in cases where motors are employed, to providefor emergency operation in either one or both directions. The inventionis applicable to single or double acting systems.

According to the present invention a pressure operated system comprisesa sliding piston assembly operated by one supply' source, `and afloating piston operated by another supply source, both the slidingpiston assembly and the oating piston as selected controlling in one orother or both directions the member to be operated.

When the invention concerns a pressure-operated motor system it ispreferable to employ a double-acting motor in which case the system maycomprise a sliding piston assembly for normal extension and retractionof motor and a floating piston working in the bore of the motor cylinderwhich also serves for normal operation of the motor, the floating pistonbeing operable by the alternative source of supply to operate the motorin one or other or both directions, When it is desired that the floatingpiston shall operate to extend the motor, the sliding piston assemblypreferably comprises a double-acting piston of any known design and ahollow piston rod, the iioating piston being placed between the annulararea of the main piston and the motor cylinder end wall; when, however,the loating piston is arranged to operate so as to retract the motor the.iioating piston is of the annular type and arranged to slide on the.main piston rodwhichis preferably hollow and provided with an abutment12 Claims. (Cl. 121-38) o against which the main piston is retained byan adjustable stop.

Various forms ofthe invention are illustrated in the accompanyingdrawings in which Figure 1 shows an arrangement in which an alternativesupply is capable of extending the motor; Figure 2 is a modied form ofFigure l whilst Figure 3 shows the alternative circuit for operatingretraction of the motor. Figures 4 and 5 show a system in which twodifferent circuits can extend or retract the motor, the differencebetween the systems residing only in the construction of motor. Figure 6shows the invention as applied to a selector valve mechanism, Figure '7being a section on the line l-l, Figure 6, and Figure 8 shows a similararrangement, Figure 9 being a section on the line 9 9, Figure 8.

Referring to the arrangement shown in Figure 1 there is provided a motorof the two-volume type in the cylinder I of which is arranged a hollowpiston rod 2 provided with an annular flange 3 acting as a seating forthe main piston 4, which is retained thereagainst by a bored securingnut 5, suitable packings 'I being-provided to seal th-e main pistonagainst the piston rod and the bore of the cylinder.

One end of the cylinder is provided with a suitable attachment meanssuch as an eye bolt lug 8, whilst the piston rod 2 at its free end isalso provided with a similar attachment means 9, in which Yis provideda= suitable inlet Il] through which liquid pressure can pass through agroove I I into the hollow piston rod, to pass therethrough via thebored securing nut into the cylinder bore I2. When pressure is soadmitted it acts on the main piston to move it to one end of thecylinder so that the motor isyextended, i. e., to the left (Figure 1).There is also provided within a cylinder a floating piston I3 which isrendered pressure-tight against the cylinder by suitable packings I 4.The cylinder is also provided with two liquid pressure inlets I6, I6,and on admission of liquid pressure through the inlet I6, the pressureacts upon the oating piston I3 tending to force it outwardly in thecylinder, the said floating piston during such movement carrying with itthe main piston 4 and piston rod 2, constituting the sliding pistonassembly. It will thus be appreciated that the motor can be extended byadmitting liquid pressure to the cylinder bore I2, either through thehollow piston rod 2 or through the inlet connection I6, and either ofthe connections I0, I6 can be employed as normal or alternativeoperation inlets. To retract the motor, liquid pressure is admitted tothe bore I2 of the cylinder throughthe connection I to the undersurfaceof the main piston 4 to act on its annular area, thus causing movementof the sliding piston assembly into the motor, carrying with it theoating piston I3.

In the alternative form shown in Figure 2 the iioating piston I3 isslidably mounted on a hollow tubular-member I'I iand which extendswithin the hollow piston rod 2, but is of such dimensions as to providefree passage for the flow of liquid pressure through the hollow pistonrid into the cylinder bore I2. In this arrangement the connections forthe supply of uidpressure are all provided on the cylinder, the -hollowpiston rod for this purpose being plugged at its outer end in a knownmanner. The hollow tubular member is formed with a bored plug I8 havinga flange I9 to provide a huid-tight seal and is in xed connection withthe cylinder I through, 'for example, a washer and circlip 2|. To extendthe motor, liquid pressure is supplied to a connection 22 at one end ofthe cylinder, which liquid pressure passes through suitablecommunication pasages E3 into the hollow tubular member I'I, thence intothe hollow piston rod 2 and into the cylinder bore I2 to act on thesliding piston assembly, and cause extension of Athe motor. Again themotor can be extended only by the supply of fluid pressure through analternative connection 24, to act on the floating piston i3 to move itinto the cylinder, carrying with it the sliding piston assembly. Toretract the motor, liquid pressure is applied at the other end of thecylinder, through connection I5, to act on the annular area of the mainpiston, thereby obtaining retraction.

In the arrangement shown in Figure 3 in which the alternative circuitoperates to cause retraction of the'motor, the oating piston I3 isinterposed between the main piston 4 and the packing glands 25 at theouter end of the cylinder, the floating piston being of an annular typearranged to slide on the piston rod 2. In this arrangement the pistonrod 2 is again provided with an annular flange 3 acting as a seating forthe main piston 4 which is retained against the iiange and on the pistonVrod by a screwing nut 26 entering the hollow Vpiston rod. Extension ofthe motor may be obtained by liquid `pressure supplied throughconnection I6-acting on the f-ull area ofthe main piston 4 whilstretraction is arranged by applying pressure through connection lil-thehollow piston rod 2 andthrough ports 21 therein adjacent the annularflange 3 so as to allow liquid pressure to enter the cylinderibore I2from the hollow .piston rod.

The otherinlet I5 to the cylinder allowsmfluid pressure to act on thefloating piston I3 to move it to contact the opposite surface of theAannular flange 3 on the piston rod 2 thereby forcing the piston rod andvmain .piston Vto the retracted position.

Referring now to the arrangement shown in Figure 4 this allows extensionor retraction yof the motor by two different circuits so that thearrangement can be utilised to obtain emergency 4extension andretractiongof the motor, as well as normal operation thereof. In thisarrangement there is provided va sliding piston assembly including amain piston Y4 and hollow piston rod 2, the piston being secured againstthe flange 3 thereon by a bored securing nut 5, the hollow piston rodhaving ports 21 as in the arrangecommunicates with the bored securingnut 5 at one end. Between the normal gland 25 closing the open end ofthe cylinder bore I2 and the main piston 4 is a oating piston 29 whichslides on the hollow piston rod 2, whilst between the main piston 4 andthe other end of the cylinder is a 'further iioating piston I3, thecylinder, as previously, being provided-with pressure supply inlets I5,IB. The hollow piston rod 2 carries the 'eye bolt attachment means 9 inwhich is provided an .inlet IIJ for supplying liquid pressure throughthe groove II to the hollow piston rod y.and Vafsecond inlet 30 forsupplying liquid pressure directly to the hollow tubular member 28within the hollow Ypiston rod 2.

Extension ofthe motor can be obtained in 4either of two ways, forexample by admitting liquid pressure through the connection I6 tooperate on the floating piston I3 which on movement contacts the slidingpiston assembly to move it into the cylinder thereby causing extensionof the motor. Extension of the motor can also be obtained by supplyingliquid pressure through theconnection 36 to the hollow tubular member 28so that the liquid pressure passes through said member 28, through thebored securing nut 5 to act on the full area of the main piston.

One way Vin which retraction of the motor can be obtained is by allowingliquid pressure to pass through the connection I5 to the cylinder boreI2 and vthus to act on the oating piston 29 which slides on the rod 2until it contacts the main piston and then causes the sliding pistonassembly to move into the motor. An alternative means of retraction canbe obtained by allowing fluid pressure to pass through the connection I0and groove II into the hollow piston 2 to pass out through the ports 21and thus act on the annular area of the main piston 4 thereby causingretraction.

Referring now to Figure 5 the motor illustrated therein is capable ofbeing operated in both directions by two alternative sources of pressuresupply of the so-called balanced type, that is wherein the area of thepressure is equal on both sides of the piston or pistons. lIn thisarrangement the hollow piston rod 2 passes through glands 25 at each endof the cylinder I and the main piston 4 is secured on the hollow pistonrod by the flange 3 and a lock nut 3l. Carried atone end of the pistonrod 2 for example by being brazed thereto is a plug 32 onto which isscrewed the eye bolt 9 for attachment of members to be moved by themotor. At the other end the vpiston rod carries a similar plug 33 andattachment member 8. The member 9 is provided vrwith ya fluid pressureinlet 34 whilst the member 8 has a similar inlet 35 so that fluidpressure can pass through either of these connections into the hollowpiston rod 2 on either side of the main piston 4; ports 35, 3l areprovided to allow communication between the two parts of the hollowpiston Vrod and the cylinder bore I2, In the said bore I2 slide twofloating pistons 38, 39 which slide on the hollow piston rod. The motoris held in fixed position by any suitable means, for example trunnionscarried by or integral with the cylinder. The system works as follows:

When fluid pressure is admitted through the connection l35 it will passinto the right-hand part of the hollow piston rod through the ports 31.to act on the right-hand side of the piston 4 and .move it towards theleft, carrying the piston rod with it. .In order to move the piston andthe piston rod :ftolthe left, iiud pressure is admitted I63, Where itretracts the 4motor 64.

through the connection 34 which passes through the hollow piston rod andthe ports 36. The motor may also be operated and this may preferably bedone by another source of fluid pressure supply,l by admitting fluidpressure at either of the connections l5 or I6. When uid pressure isadmitted through the connection I6 it passes into the bore 2 of thecylinder to act on the floating piston 39 and move it towards the leftso that it eventually carries with it piston 4 and the piston rod. Whenfluid pressure is admitted through the connection I 5 it similarlypasses into the cylinder bore, similarly acts on the oating piston 38and moves the main piston 4 to the right. It will thus be appreciatedthat the motor can be operated in both directions by alternative sourcesof pressure supply.

In all cases in which a double-acting motor has been described it willof course be clear that in place of a double-acting motor asingle-acting motor could be provided which could be biassed into oneposition by a spring or by the weight of the part to be moved.

It will, of course, be appreciated that in all the constructionsreferred to above where two connections are provided to obtain eitherextension or retraction, either of these two connections can be employedas the normal method of extension or retraction, and the other as theemergency connection.

If the underearriage of an aircraft is operated by a motor, thearrangement may be such that very little force is needed to lower it andFigure 6 illustrates an arrangement of the motor adapted for thispurpose.

With arrangements described above the motor may have incorporatedtherein a mechanical lock, for example of the type described in theBritish patent specication 527,225, or a load limiting device of thetype described in the specification of British Patent 652,094.

The invention may be applied to a selector valve mechanism adapted tooperate a motor for lowering the undercarriage in cases of emergency. Inthis case the selector valve mechanism is operated by one or other ofthe two alternative pressure supplies, and in one case the supply entersthe selector valve body and moves the valve so that pressure can beadmitted to the motor to retract the motor. The alternative pressuresupply, however, enters the selector valve body and operates a floatingpiston which in turn ensures that the valve is so positioned in theselector body that exhaust from the motor cylinder can pass toatmosphere or tank. Figures 6 to 9 illustrate two arrangements in whichthe invention is applied to a selector valve mechanism.

Referring to Figures 6 and 7 the selector valve indicated generally at48 is adapted to be operated both manually and electrically and for theclearer understanding of the invention a brief description of itsconstruction and normal operation will now be given.

The selector 48 is provided with a valve in the form of a piston 65 anduid connections 50, 5|, 52, 53, 54, 55, connections 5|, 52 and 53 eachbeing provided with a port, namely 56, 51 and 58. If the selector ismanually operated then fluid pressure enters connection 52 from line 59,passes through ports 51 and 69, passage 6| into ports 62 and` 56, thencethrough'connection 5| and line The uid pressure from the other side ofthe piston of -motor 64 returns through line 66, connection 53 into 6ports 58, 61, 68 and 69, and passes through corl nection 18 to exhaust.

The uid pressure line 59 is provided with two branch lines 1|, 12 foruse when the selectoris operated electrically which lead into theunderside of shuttle valves 13 and 14. The shuttle valves are ofidentical construction and each conl tain a valve and valve spindle 15which carries or has formed integrally therewith the armature of each`of a pair of solenoids T6, 11, said shuttle valves 13, 14 beingprovided with pipe lines 18, 19 which lead into an exhaust line 80.Shuttle valve 13 is connected by line 8| to one side of the selec-l torpiston 65 and shuttle valve 141s connected by a line 82 to the otherside of said piston.

It will be appreciated that. the normal operation of the system is asfollows: to retract the motor 64 the solenoid 11 is actuated and itsarmature will carry the associated spindle 15 upwardly, thus opening theshuttle valve 14, this action allowing uid pressure supply coming fromlines 59 and 12 to pass through into line 82, thence through connection54 and port 83 into the bore 84 of the selector, thereby moving thepiston 65 to the left, the fluid on the other side of said piston 65passing through port 85, connection 50, line 8|, through lines 18 and 88to exhaust. To extend the motor 64, solenoid 16 is actuated in a likemanner and the reverse procedure effected.

If in the case of emergency it is desired to retract the motor 64containing an emergency piston 86, uid pressure is supplied through theemergency line 81, this line branching out into lines 88 and 89, so thatpressure will act substantiallysimultaneously on the emergency piston 86and the oating piston 98 of the selector valve 48. When in the case ofemergency fluid, pressure is admitted by any suitable means into theline 81 and thence to line 88, it will pass through the connection 55and port 9| into the bore to the right of the floating piston 98 of theselector valve 48 where it will act upon the floating piston 98, saidpiston 96 being moved in the bore of the selector 48, together with thepiston 65 if the latter is not in the left hand position already.Substantially simultaneously fluid pressure will act on the emergencypiston 86 of the motor 64 thus closing said motor and lowering theundercarriage.

Figures 8 and 9 show a selector valve embody- 4 ing the invention,capable of operating a motor with alternative fluid pressure in bothdirections. Housed within the lbore 84 of the selector valve are thefloating pistons and 92, the selector valve being provided with twoadditional fluid connections 93, 94, the alternative source of fluidsupply being preferably, but not necessarily, operated by a selector ofthe type described in connection with Figures 6 and 7.

The operation of the system is such that if the motor 64 is to beoperated by uid pressure from line 59 the selector 48 acts as that shownin Figures 6 and 7, and when the alternative source of fluid pressuresupply from line 96 is employed pressure is admitted into the line 96 byany suitable means, e. g. a cock.

To retractl the motor 64 shuttle valve 91 is operated to move the piston98 to the right, fluid then passing through the selector 95, thence intobranch lines 81, 88, 89. The pressure will pass from line 89 into themotor 64, act on the piston 86 carrying the piston 99 with it, andretract said motor 64. At the same time,` iluid pressure will enter .theselector .valve 48 from line 88 through .connections 9,3 and 9|, and act on thaoating 7 'piston 90 moving it to 'the leftLtogether with 'thepiston 65 of said selector 48, thus enabling the uid from the right-handside of the fpiston 99 ofthe motor 64 to pass to exhaust.

When it is desired to extend the rhetor, duid pressure is admittedthrough the'valve |00 thus moving the piston 98 to the left, suchmovement allowing Vfluid from line 96 to pass through the selector 95into line ||l| and its branch lines |02, |03. The uid from line |02 willenter motor 64 Where it will act on the piston |04 to move it to theleft, together with the piston99,"thus extending the motor.

-At the same time pressure will pass -fromv line |03 through connection91|,` port `|05 into the bore 84 of the selector 48, where it, will acton the oating piston 92 and move it tothe right carrying the piston 65Vof the selector 48 with it. When this occurs fluid from the right handside of the floating piston 90 will pass through lines Y88 and 81, aswell as the selector 95 into line |c6,'and return by line |01 toexhaust. lFluid from the left-hand side of piston 99 of the motor 64will thus be allowed to pass to exhaust by means of line |08 via theselector 48 and line 80.

What I claim is:

1. In a uid pressure system for moving a member, a motor comprisingcylinder'meana a piston assembly element including a main piston andpiston rod slidable in Vsaid cylinder means, and a iioating pistonelement slidablev within said cylinder means, said floating'pisto'nelement sealing onel portion of said cylinder means againstcommunication with and 'thereby isolating it from other portionsthereof; means connecting said motor to said member; two in- ,dependentiiuid pressure supply sources; and

vother portions of said cylinder means are in L communication with aleak the pressure otui-d introduced into said isolated cylinder portionwill not be'diminished and said motor will be oper-- 'ated a full strokeby said floating piston irrespective of the leak.

2. Fluid pressure system apparatus` as 4set forth in claim l in whichthe main piston is a double acting piston,` the selector mechanism beingoperable for directing iiuid under pressure from one supply source intoportions of said cylinder on opposite sides of said main pistonselectively, and being operable for directing uid under pressure fromthe other of said vsupply `sources into the said isolated cylinderportion.

3. Fluid pressure `system apparatus as set forth in claim 2 in which thepiston rod ofthe piston assembly element is hollow to provide for iiowof pressure uid from said one of -said sources into a portion ofsaidcylinder on one side of said main piston other than :said isolatedcylinder portion.

4. Fluid pressure system 'apparatus as set forth in claim 3, inwhich theVconnection of. the

piston rod to the main piston prov'i'des'an annular area on one side ofsaid piston effective for 'the application .of pressure for moving saidpiston assembly element, the floating rpiston being positioned betweenthe opposite side of said piston andthe adjacent end of the cylinder.

5. Fluid pressure system apparatus as set forth in claim 3, in which the'connection of the piston rod to the 'main piston provides an annulararea on one side of said piston eiective for the application of pressurefor moving said piston assembly element, the iloating piston beingpositioned between the side of said -piston having said annular area andthe adjacent-end of said cylinder.

6. Fluid pressure system apparatus as set forth in claim 5 in which `theiioating piston is annular and slidable on said piston rod which extendsthrough said floating piston, the periphery of said iioating pistonhaving sealed sliding engagement with the walls of said cylinder.

7. Fluid pressure system apparatus as set forth in claim 3 in which saidcylinder has two pressure supply inlets'independent of the hollow pistonrod, one of said inlets being located to introduce iiuid into saidisolated cylinder portion, and the other of said inlets being located tointroduce fluid into said cylinder on the side of said main pistonopposite the side thereof at which duid lmay be introduced through saidpiston rod.

8. Fluid pressure system apparatus as set forth in claim 3 including ahollow tubular member mounted in said cylinder at one end thereof andprojecting into said hollow piston rod, all the connections from saidflow-control means and said motor leading through walls of said cylinderand including a connection leading through a cylinder wall into saidhollow tubular member, a connection leading through a cylinder wall intosaid isolated cylinder portion, and a connection leading through acylinder wall into the portion of said cylinder through which saidpiston rod extends.

9. Pressure supply system apparatus as set forth in claim 3 in whichsaid hollow piston rod is formed with ports providing communicationbetween the interior of said piston rod and the portion of saidvcylinder -through which said piston rod extends.

10. Pressure supply system apparatus as set forth inclaim 3 in whichsaidhollow piston rod is open at the end thereof at which it isconnected to said main piston to provide communication between theinterior of said hollow piston rod and the portion of said cylinderopposite the portion thereof through which said piston rod extends.

ll. Pressure supply systeml apparatus as set forth in claim 3 includingtwo oating pistons respectively sealing off two isolated cylinderportions, said hollow piston rod having ports therein A adjacent to oneside of said main-piston, a hollow tubular member fixed to said mainpiston and 'communicating with said cylinder on the side of said mainpiston opposite said ports, and projecting -through said hollow pistonrod in spaced relation thereto, and pressure supply connectionscommunicating respectively with said isolated cylinder spacesindividually, with said tubular member, and with the spacebetweensaid'tubular member and said hollow piston rod.

l2. Pressure supply system apparatus as set Vforth in claim 3 in whichthe hollow piston rod projects through each end of the cylinder, theprojecting end portions of said rod having respective-means forattachment' to members to be operated, and ports in said cylinder rod oneach side of said main piston, there being a l0 UNITED STATES PATENTSNumb N D oating piston in said cylinder on each side of 2 00E-,$5157Pelto'me June $81935 said main Piston- 2396984 Broadst-re't'- Y- Mar.19'1946 STANLEY HACKNEY- 5 2,397,106 Hauer Mar. 26, 1946 REFERENCESCITED FOREIGN PATENTS The following references are of record in theNumber COllntly Date file of this patent: '73,412 Switzerland Oct. 2,1916 Switzerland Apr. 16, 1920

